This invention relates to a heat conserving damper control which regulates the draft within the flue when the furnace is operating and which closes the flue to reduce heat loss when the furnace shuts off.
Flue damper controls are devices designed to conserve heating fuel. Optimally, these devices adjust the draft in the flue when the burner is on and close the flue to retard the loss of heat when the burner goes off. The need for fuel-saving devices of this nature is apparent in times of fuel shortages and rising fuel prices.
Many damper controls have been described in the prior art. Most of these devices consist of dampers which are opened and closed in response to a room thermostat. For example, U.S. Pat. No. 1,773,585 to Klockau discloses a damper subject to flue pressure on one side and atmospheric pressure on the other. When the room thermostat calls for heat, an electromagnet drives the damper open against the influence of a counterweight. While the furnace is operating, the damper can float through a limited range of positions to regulate the draft within the flue. When the thermostat shuts off the furnace, the circuit is broken and the weight swings the damper closed, preventing the loss of heat. Similar power-assisted dampers are described in U.S. Pat. Nos. 1,833,888 to Barker and 2,319,652 to Young.
In U.S. Pat. No. 2,113,440 to Cole, a damper control is disclosed which utilizes a pressure-responsive mechanism separate from the damper to control the attitude of the damper. In this patent, a vane, subject to external atmospheric pressure on one side and to the pressure in the flue upstream from the damper on its other side, is connected to the damper and regulates the draft inside the flue. This damper control, like the other prior art devices, employs a motor controlled by a thermostat to drive the damper to its closed position when the burner shuts down.
It is therefore an object of the present invention to provide a damper control for a furnace which operates solely in response to external atmospheric pressure and to flue pressure.
It is a related object to provide a damper control for a furnace which regulates the draft in the flue when the furnace is on and closes the damper when the furnace turns off, all without assistance from an external power source.
It is another object of the present invention to provide a damper control for furnaces which is simple, inexpensive, and easily installed on existing smoke pipes.